Download DCAS Review of Energy Across the Systems

DCAS Review of Energy Across the
Systems
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1. Radio waves, visible light, and x-rays are
examples of electromagnetic waves that
always differ from each other in
A. amplitude
B. intensity
C. temperature
D. wavelength
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D. wavelength
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Electromagnetic waves are classified by their wavelength. Gamma rays have the
shortest wavelength and radio waves have the longest. Visible light falls
somewhere in the middle of the spectrum. The full range of the electromagnetic
waves is called the electromagnetic spectrum.
The only part of the electromagnetic spectrum that you can see with your eyes is
visible light. Visible light includes all the colors of the rainbow: red, orange, yellow,
green, blue, indigo, and violet. Red light has the longest wavelength; violet light
has the shortest. When all the different colors of light are combined, you see them
as white light.
ROYGBIV red orange yellow green blue indigo violet
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2. A sound wave can be transmitted through all
of the following except
A. a gas
B. a liquid
C. a solid
D. a vacuum
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D. Vacuum
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Unlike light, sound waves need a medium (matter) to travel through. Sound cannot
exist in a vacuum. Like light, sound travels at different speeds through different
materials. In general , sound travels faster through solids than through liquids, and
faster through liquids than through gases. Sound waves also travel faster through a
warmer medium than through a cooler medium
Frequency is the number of waves produced in a given time. The frequency of a
sound wave determines its pitch, or how high or low the sound is. The higher the
frequency of a sound wave, the higher the pitch. Most humans can perceive sound
waves within a frequency range of 20 to 20,000 Hz, or wave per second. .
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3. Heat energy is most closely associated with
which one of the following?
A. gravitational potential energy
B. Kinetic energy
C. Light energy
D. Chemical energy
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C. Light Energy
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4. Why does wearing a light colored shirt on a
hot day feel cooler than wearing a dark
colored shirt?
A. White objects absorb all visible light and
dark objects reflect all visible light
B. Both white and dark objects reflect all
visible light
C. White objects reflect all visible light, where
black objects absorb all visible light
D. Both white and dark objects reflect all
visible light
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C. White objects reflect all visible light,
where black objects absorb all visible light
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5. Two oppositely charged objects are
separated by a small distance. The objects are
then moved three times farther apart from
each other. Which of the following statements
best describes what happens to the electrical
force between the objects?
A. The force of attraction increases.
B. The force of attraction decreases.
C. The force of attraction becomes zero.
D. The force of attraction stays the same.
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B. The force of attraction decreases.
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Electric force and magnetic force are closely related. This is because both are
caused by negative and positive charges in matter. Atoms, which make up all
matter, contain a positively charged nucleus and a negatively charged cloud of
electrons. When charges from one piece of matter interact with those of another
piece of matter, they produce both electric and magnetic forces. These forces can
be attractive (pulling the objects together) or repulsive (pushing the objects apart)
The electric force between two charged objects varies depending on the amount
of charge on each object and the distance between them. The electric force
between two objects is proportional to the product of the charges on the objects.
If the charge on one object is doubled, the electric force between the objects will
also be doubled, as long as the distance between the objects remains the same.
As you increase the distance between two charges, if everything else is the same,
the electric force decrease the further they are apart. .
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6. X-ray waves and infrared waves are both
electromagnetic waves. Which of the following
describes another property x-ray waves and
infrared waves share?
A. Both waves are transverse.
B. Both waves have the same frequency.
C. Both waves have the same wavelength.
D. Both waves travel at the same speed in a
vacuum.
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A. Both waves are transverse.
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When the oscillation (back and forth or up and down motion) of a wave is
perpendicular to the direction in which the wave travels, the wave is called a
transverse wave. The peak, or highest point, of a transverse wave is the crest. The
valley, or lowest point, between the two crest is the trough. Electromagnetic
waves and a secondary wave (S wave) are examples of transverse waves.
A longitudinal wave is a wave whose oscillation is parallel to the direction in which
the wave travels. For example, if you set a spring on your desk and push the end of
the spring over and over, you create regions where the coils are closer together
(compressions) and regions where the coils are farther apart (rarefactions). The
compressions and rarefactions move in the same direction in which the wave
travels. Examples of longitudinal waves are sound waves and a type of seismic
wave called a primary wave (P wave)
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7. A car with its horn sounding approaches a
group of students. Assume the car’s horn
produces sound waves with a constant
frequency.
Which of the following statements best
explains why the students hear a higher pitch
as the car approaches than when it is stopped?
A. The sound waves increase in speed as the
car approaches the students.
B. The sound waves decrease in speed as the
car approaches the students.
C. The sound waves are heard at a lower
frequency as the car approaches the students.
D. The sound waves are heard at a higher
frequency as the car approaches the students
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D. The sound waves are heard at a higher frequency as the car
approaches the students
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The higher the frequency, the higher the pitch. When the car is coming toward you
with its horn blowing, it gets louder the closer it gets to you. When the car is
moving away from you, the lower the frequency and lower pitch.
If an ambulance is moving toward you, the sound waves from the siren are
compressed in the direction of motion. The distance between the wave fronts is
shortened, though the wave speed remains the same. The sound waves reach your
ear at a higher frequency; they sound higher pitched than they would if the
ambulance were at rest. If an ambulance is moving away from you, the frequency
at which the waves reach your ear is less, and you hear the sound of the siren at a
lower pitch than you would if the ambulance were not moving . This change in the
observed frequency of a wave is called the Doppler effect.
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8. A 5 kg rock and a 10 kg rock are dropped
from a height of 10 m on Earth. Which of the
following statements describes what happens
to the potential energy of the rocks?
A. Neither rock loses potential energy because
no work is done on the rocks.
B. Both rocks lose the same amount of
potential energy because they fall from the
same height.
C. The 10 kg rock loses more potential energy
than the 5 kg rock because the 10 kg rock falls
faster.
D. The 10 kg rock loses more potential energy
than the 5 kg rock because the 10 kg rock has
more mass.
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D. The 10 kg rock loses more potential energy than the 5 kg rock
because the 10 kg rock has more mass.
• Gravitational potential energy depends on
both mass and height. Because it is caused by
the force of gravity, gravitational potential
energy near Earth depends on both the mass
of the object and height of the object relative
to Earth’s surface. If two objects of different
masses are at the same height, the heavier
object has more gravitational potential energy
than the light one does.
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9. Which of the following statements is true
according to the law of conservation of
energy?
A. Energy cannot be created
B. Energy cannot be destroyed
C. Energy can be converted from one form to
another
D. All of the above
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D. All of the above
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10. A large container of cold water is moved
from a refrigerator to a table. A hot piece of
metal is placed into the water. Which of the
following best describes the final temperature
of the metal?
A. higher than the final temperature of the
water
B. the same as the final temperature of the
water
C. lower than the initial temperature of the
water
D. the same as the initial temperature of the
water
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B. the same as the final temperature of the water
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11. Which of the following statements best
describes the visible spectrum of light as seen
by the human eye?
A. The lowest frequency appears red, and the
highest frequency appears violet.
B. The lowest frequency appears red, and the
highest frequency appears yellow.
C. The lowest frequency appears green, and
the highest frequency appears violet.
D. The lowest frequency appears green, and
the highest frequency appears yellow
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A. The lowest frequency appears red, and the highest frequency
appears violet.
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12. The diagram above represents a bicyclist at the top of a hill with 4 points labeled W,X,Y and Z.
Assume that the bicyclist does not apply the brakes as he rides down the hill. At which point will the bicyclist’s kinetic
energy be closest to zero?
A. point W
B. point X
C. point Y
D. point Z
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A. Point W
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A
13. The diagrams below show a man swinging a golf club.
The kinetic energy of the golf club at point Y is more than the potential energy of the
club at point X. Which of the following statements best explains why this fact does not
violate the law of conservation of energy
A. Gravity is constant from point X to point Y.
B. Air resistance is greater at point Y than at
point X.
C. Acceleration due to gravity is greater at
point Y than at point X.
D. Energy is added by the man to the golf club
from point X to point Y.
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D. Energy is added by the man to the golf club from
point X to point Y.
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14. A student swings a bat horizontally, making
contact with a ball thrown to her. The ball
leaves the bat, and the bat continues moving
through the rest of the swing.
Which of the following statements describes
the change in energy necessary to do work on
the ball?
A. All the kinetic energy of the bat is converted
to work.
B. All the potential energy of the bat is
converted to work.
C. Some of the kinetic energy of the bat is
converted to work.
D. Some of the potential energy of the bat is
converted to work
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C. Some of the kinetic energy of the
bat is converted to work
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15. Two wave forms traveling through a
substance are depicted below. Wave A has
twice the frequency of Wave B, but Wave B has
twice the amplitude of Wave A. Which wave
can deliver the greatest amount of energy
every second?
A. Wave A can deliver more energy
B. Wave B can deliver more energy
C. Both waves can deliver the same amount of
energy
D. Can’t be determined
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C. The same
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The amplitude of a wave is the distance a wave oscillates from its resting position.
The larger the amplitude, the more energy carried by the wave.
Wavelength is the distance from any point on one wave to a corresponding point
on an adjacent wave.
Frequency is the number of oscillations produced in a certain amount of time. The
greater the number of oscillation per second, the higher the frequency . The
higher the frequency, the more energy carried by the wave.
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16. The sequence of energy changes shown in
the diagram (energy chain) best explains with
event?
A. a flashlight is on
B. a candle burns
C. gasoline burns to propel a car
D. electric energy runs a refrigerator
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C. Gasoline burns to propel a car
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17. Which of the following is an example of an object with elastic potential energy?
a.
a wind-up toy that has been wound up
b.
a compressed basketball
c.
a stretched rubber band
d.
all of the above
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D. All of the above
• An object gains a different type of potential energy when it is stretched.
The potential energy associated with objects that can be stretched or
compressed is called elastic potential energy. The energy stored in a
stretched object, such as a bow, rubber band or spring, is elastic potential
energy.
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